Sure, there are some excellent calculators in the Android Market, but do any of them make you hesitate for a minute when looking at them to figure out whether you are staring at a phone or a smaller version of your favorite Texas Instruments machine? Doug Melton's ports of the popular AlmostReal TI-83, TI-85, and TI-86 emulators to Android are so successful, most of your professors wouldn't even know the difference if they saw one of these on your desk.